The present invention relates to a throttle control apparatus which electronically controls a control valve for controlling a suction air amount of an internal combustion engine mounted on a vehicle by using an actuator such as a motor etc.
In recent years, the throttle control apparatus for a vehicle has been shifting from the one employing the method of mechanically controlling the position of a throttle valve in an interlocked manner with an acceleration pedal to the one of an electronic control type which electronically controls a throttle valve by using an actuator such as a motor etc. to supply an optimum amount of air in accordance with the operation condition of an engine. Such a conventional throttle control apparatus of an electronic control type is arranged in a manner, as described in JP-A-61-8441, for example, that a signal relating to an operation condition such as an output signal of an acceleration sensor for detecting a depressed amount of an acceleration pedal is subjected to the calculation processing thereby to set a target throttle opening degree of a control valve. Further, in this throttle control apparatus, a throttle sensor for detecting the position of the control valve is provided, then an actual throttle valve opening degree is calculated from the output value of the throttle sensor, and the position of the control valve is subjected to the feedback control by using an actuator such as a motor etc. until the actual throttle valve opening degree becomes equal to the target throttle valve opening degree.
Further, another conventional throttle control apparatus of an electronic control type is arranged in a manner, as described in JP-A-10-306735, for example, that it is required to secure the safety of a throttle body to be controlled since the throttle position control operation of the throttle body is entirely performed by using electric signals, and a default mechanism for mechanically supplying an air amount capable for self-propelling is provided so that a vehicle can move to a repair shop when the apparatus becomes faulty.
However, the conventional throttle body provided with the default mechanism is configured in a manner that, when an abnormality of a sensor etc. occurs, a power source for the actuator driving system is cut off and the throttle valve is mechanically restored to a default opening degree due to the biasing force of a spring etc. Thus, the throttle body is arranged to have a non-linear axial torque characteristics. Further, the throttle valve is controlled in a manner that the throttle body having the non-linear axial torque characteristics is controlled by employing a control method such as a PID feedback control etc.
The integration item serving for converging the subject to be controlled to the target throttle valve opening degree has a second order lag characteristic and also has a non-linear characteristic since the controlled subject system has a non-linear characteristic due to the default mechanism. Thus, it takes a long time for the integration value to converge. In particular, when performing such a response that the target throttle valve opening degree crosses over the default opening degree, there arises a problem that the response time and the converging time become large.
Accordingly, an object of the present invention is to provide a throttle controlling device which can obviate the aforesaid problem of the prior art.
Another object of the present invention is to provide a throttle controlling device which can make both the response time and the converging time shorter.
(1) In order to attain the aforesaid object, according to an aspect of the present invention, the present invention is arranged in a manner that in a throttle control apparatus which controls a position of a throttle valve of an electronic control throttle body having a default mechanism for securing self-propelling of a vehicle at a time of faulty by using an actuator on a basis of a target throttle valve opening degree obtained by an engine control unit, when a target throttle valve opening degree inputted from the engine control unit crosses over a default opening degree of the default mechanism, a correction value having been added is set to an initial setting value, and a correction value having been calculated hereinafter is added to the initial setting value to thereby perform a feedback control.
According to such an arrangement, when the target throttle valve opening degree crosses over the default opening degree, the correction value is set to the initial setting value, so that the response using an integration item can be made quicker and so both the response time and the converging time can be made shorter.
(2) In the arrangement of (1), preferably, the initial setting value is set to 0.
(3) In the arrangement of (1), preferably, a dead band area including the default opening degree is provided, and when the target throttle valve opening degree inputted from the engine control unit crosses over the dead band area, an integration value having been added is set to an initial setting value, and an integration value having been calculated hereinafter is added to the initial setting value to thereby perform a feedback control.
(4) In the arrangement of (3), preferably, a value of the dead band is xc2x11.5 degrees.